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Mature follow up from multiple randomized trials have demonstrated the safety and efficacy of external beam partial breast irradiation (PBI) for appropriately selected patients with early stage breast cancer. Despite this evidence, external beam PBI remains underutilized. In this user guide we outline patient selection, workflow, and address possible challenges to aid in implementation of evidence-based external beam PBI.Review of the current guidelines for PBI suitability, surgical considerations, treatment technique, simulation, contouring, and treatment planning, citing the latest published literature to support PBI utilization.Prospective data supports the use of 30 Gy in 5 fractions delivered with intensity modulated radiation therapy on a daily or every other day basis for a significant proportion of early stage breast cancer patients. The surgical cavity must be clearly visualized on treatment planning scan, recommend 3-5 weeks post-operatively, and the recommended clinical target volume expansion on the surgical cavity is 0.5-1.0 cm. A planning target volume expansion, based on motion management and image guidance, of 0.5-1.0 cm should be used. Organ at risk dose constraints of heart V3Gy ≤10% and contralateral breast Dmax ≤1 Gy are often achievable.Five fraction external beam PBI is a highly effective treatment with very limited toxicity for patients with early stage breast cancer following breast conserving surgery. Commonly utilized intensity modulated treatment planning techniques with plan delivery on standard linear accelerators results significant normal tissue sparing and makes implementation feasible at most radiation oncology centers.

Introduction We sought to evaluate the safety and efficacy of stereotactic body radiation therapy (SBRT) as salvage treatment for local recurrence after prior surgical resection for non–small-cell lung cancer (NSCLC). Materials and Methods We surveyed our prospective lung SBRT registry for patients who received salvage SBRT (sSBRT) for local recurrence after previous resection of a primary NSCLC. Following sSBRT, local control, distant metastases, overall survival, and treatment-related toxicity were evaluated. Results From 2004 to 2017, 48 patients met inclusion criteria. At initial surgery, 44 (83%) patients had stage I to II disease, and surgical approaches were 47.9% wedge resection, 4.2% segmentectomy, 43.8% lobectomy, and 4.2% bilobectomy. The median time to local recurrence after surgery was 26.4 months, and 36 (75%) recurrences were biopsy-proven. Surgical salvage was not possible owing to un-resectability or underlying comorbidities in 45 (93.8%) patients. Most (68.8%) patients received 50 Gy in 5 fractions. The median follow-up after sSBRT was 22.6 months (range, 3.8-108.8 months). Eight (16.7%) patients experienced local or lobar failure, and 9 (19.1%) patients had nodal failure at a median of 12.5 months (range, 2-66.1 months). Nineteen (39.6%) patients failed distantly at a median of 11.4 months. The median overall survival after sSBRT was 29.3 months. A total of 72.9% of patients experienced no toxicity after sSBRT. Three (6.3%) patients developed grade III toxicity (cough, atelectasis, or soft tissue necrosis) following sSBRT. Conclusions Similar to SBRT for primary early stage NSCLC, sSBRT for local relapse following surgical resection of NSCLC offers high rates of local control with limited toxicity. Distant failure remains the primary pattern of failure.

e19407 Background: The purpose of this study was to evaluate the impact of a continuous improvement process aimed at reducing time to treatment on minimizing the number of days spent to complete pre-treatment visits and the associated costs for patients with non-metastatic breast cancer. Methods: System-wide initiatives were implemented in 2015 to minimize time to treatment initiation (TTI), by incorporating lean process strategies and enhanced coordination. Patient and treatment information was obtained through an IRB-approved registry for the years 2015 and 2018. Average number of days spent to complete visits, TTI, and associated patient costs including driving expenses, parking, food, childcare, and lost wages were calculated and compared between the years 2015 and 2018. Results: In 2015, the median TTI was 43.5 days and the average number of separate days spent to attend multidisciplinary visits prior to first treatment was 1.86. These were reduced to 29 days and 1.52 visits, respectively, in 2018 (p < 0.0001 for both). When evaluating treatment visits by surgical procedure, the average number of visits was reduced regardless of surgical procedure. The average number of visits was highest for patients undergoing mastectomy with reconstruction (2.34 in 2015, reduced to 1.65 in 2018, p < 0.0001). A single visit to complete treatment planning was associated with patient costs of $249 as compared with multiple trips costing $491 for 2 visits and up to $1,226 for 5 visits. Conclusions: In breast cancer patients, implementing a continuous improvement process to reduce time to treatment was associated with fewer visits required prior to treatment initiation, resulting in lower patient costs.

We sought to evaluate time trends and correlates of the use of a radiation tumor bed boost (TBB) after breast-conserving surgery and either conventional or hypofractionated whole-breast irradiation (CWBI or HWBI) for patients with early stage breast cancer.The National Cancer Database was queried for patients diagnosed between 2012 and 2016. We evaluated the utilization of TBB before and after publication of the Society of Surgical Oncology-American Society for Radiation Oncology margin guidelines in relation to sociodemographic variables, treatment facility, tumor characteristics, and whole-breast fractionation.The population included 380,387 patients, of whom 76.7% received a TBB. Utilization of TBB decreased over time (2012-2013: 79.2%; 2014: 76.6%; 2015-2016: 74.7%; P.001); this was seen for most subgroups evaluated. Rates of TBB differed by facility type and region. There was a decrease in TBB use in patients treated with CWBI over time (2012-2013: 84.9%; 2014: 83.5%; 2015-2016: 82.3%; P.001) but an increase among patients treated with HWBI (2012-2013: 55.5%; 2014: 60.7%; 2015-2016: 65.1%; P.001); this was also seen for low-risk patients (age70 years, negative margins). Among patients undergoing HWBI, TBB was more frequently used when 15 fractions were used compared with 16 fractions (76.8% vs 59.1%; P.001).The use of TBB decreased over time, coinciding with the publication of new margin guidelines, for patients receiving CWBI and those with negative margins, but TBB use increased for patients treated with HWBI. Hence, fractionation regimen is a critical variable in analyzing changes over time in the practice patterns of TBB.

Breast cancer treatment often requires multi-disciplinary evaluation, which can require multiple visits, delaying time to treatment initiation (TTI). The present analysis evaluated the impact of system-wide initiatives to reduce TTI by evaluating TTI for patients completing treatment evaluation in a single visit compared with those having multiple visits. The results demonstrated that patients who completed multi-disciplinary evaluation in a single visit had a reduced median TTI (27 vs 32 days, P = .002), which was seen for patients undergoing initial surgery (28.0 vs 33.5 days, P = .01) as well as for those undergoing neoadjuvant systemic therapy (22.5 vs 29 days, P = .05).

PURPOSE/OBJECTIVE(S) To report outcomes for women with pT1-2N1M0 breast cancer undergoing mastectomy and sentinel lymph node biopsy (SLNB) without completion axillary dissection, and to investigate the effect of post-mastectomy radiation therapy (PMRT). MATERIALS/METHODS Data from 5 North American institutions were pooled to include women with pT1-2N1M0 breast cancer from 1997-2015 who underwent mastectomy with a positive SLNB and ≤ 5 lymph nodes (LNs) resected. All patients were clinically N0 and none received neoadjuvant chemotherapy. Competing-risks regression was performed to identify factors associated with overall recurrence (OR), inclusive of locoregional (LR) and distant recurrence (DM). RESULTS Among 871 patients included, median age at diagnosis was 57 years, 92% were ER/PR-positive, 85% HER2-negative, and 60% received adjuvant chemotherapy. The 500 (57%) patients who received PMRT were significantly younger, had larger tumors, more positive LN, lymphovascular invasion (LVI), extracapsular extension (ECE), HER2-positive disease, and more frequently received adjuvant chemotherapy (all P < 0.05) compared to those not receiving PMRT. Median number of lymph nodes sampled in each group was 3 (range: 1-5). At a median follow up of 5.2 years, the 5-year cumulative incidence rates of LR, DM, OR, and breast cancer mortality (BCM) were 2%, 4%, 5%, and 3%, respectively. The 5-year rates of disease-free survival (DFS) and overall survival (OS) were 87% and 91%. LR was the only endpoint with a statistically significant difference between those receiving PMRT (0.4%) as compared to those without PMRT (3.9%), P < 0.001. On univariable competing risks regression, tumor size, nodal ratio, grade, LVI, and ER/PR status were significantly associated with OR and were included in multivariable analysis. On multivariable competing risks regression, larger tumor size (HR 1.47, 95% CI 1.19-1.81, P < 0.001), grade III (HR 1.81, 95% CI 1.07-3.05, P = 0.03), higher nodal ratio (HR 2.86, 95% CI 1.01-7.69, P = 0.049), and LVI (HR 2.04, 95% CI 1.27-3.28, P = 0.003) were significantly associated with increased risk of OR. PMRT was associated with decreased risk of OR (HR 0.60, 95% CI 0.26-1.00, P = 0.05), though this effect did not reach statistical significance. CONCLUSION In selected patients undergoing mastectomy and SLNB without completion axillary dissection for pT1-2N1 breast cancer, larger tumor size, higher grade, increased nodal ratio and the presence of LVI are associated with increased risk of overall recurrence. Further studies are needed to identify which subset of patients may benefit most from PMRT.